(1) Field of the Invention
The present invention relates generally to bass drum pedals, and more particularly to an improved spring return system for bass drum pedals and other foot-operated musical instruments.
(2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97, 1.98
Although bass drum pedals 11 on the market today use a wide variety of different apparatus for driving a beater or hammer against a drum head, they all rely on three basic components connected to a drive shaft: a beater 12, a foot plate 14, and a spring return 16, as shown in FIG. 1 of the drawings. The beater 12 includes a head or hammer 18 mounted on a distal end of a shaft 20, with the proximal end of the shaft attached to a rotatable drive shaft 22 on a frame 24. Rotation of the drive shaft 22 swings the beater 12 through an arc equal to the angular rotation of the drive shaft 22, towards and away from a drum head 26, to thereby cause an impact of the beater 12 with the drum head 26. The drive shaft 22 is linked to a pivotable footplate 14 with a cable or chain 28, such that depressing the footplate 14 will cause the drive shaft 22 to rotate and swing the beater 12 towards the drum head 26. The spring return 16 is connected between the drive shaft 22 and the frame 24, and biases the drive shaft 22 to return the beater 12 from its impact with the drum head 26 while simultaneously raising the depressed footplate 14 to permit a subsequent stroke.
While there are many different ways that prior art pedals actually connect spring return 16 to driveshaft 22, the most common is by the releasable attachment of a link 30 to drive shaft 22. This may be accomplished by a set screw 32, or any other means that locks the link 30 in the desired position on shaft 22, so that link 30 will rotate with shaft 22. One ear 34a of a coil spring 34 is engaged through an aperture 36 in link 30. The opposite ear 34b is engaged through an aperture in one end of a threaded rod 38. Threaded rod 38 is journaled through an aperture in a flange 40 on frame 24. A threaded nut 42 is threaded on rod 38 below flange 40, to permit adjustment of the length of rod 38 projecting above flange 40, and thereby adjusting the length of spring 34.
In general, prior art pedals 11 allow only two spring system adjustments—the altering of the rest point, and the altering of the pre-load length of the spring 34. The rest point is defined as the mechanical position of the bass drum pedal 11 at which the footplate 14 is at rest, i.e. when not being acted upon by a player. This position is also the point at which the spring 34 is under the least amount of tension. FIG. 1 shows a prior art bass drum pedal 11 in the rest position, with the beater shaft 20 resting in a position approximately 60°-80° from drum head 26 with the drive shaft 22 rotated the same degree of rotation in the negative direction. The total operational driveshaft rotation, as measured from 0° at the point of impact of beater hammer 18 with drum head 26 to the point at which spring 34 stops the reverse swing of beater 12, is about 95°-120°.
The rest position of pedal 11 may be adjusted in prior art models by releasing the link 30 from driveshaft 22, which occurs by loosening set screw 32. The desired rest position of beater 12 may then be adjusted by rotating the beater 12 and driveshaft 22. Setscrew 32 is then tightened back onto driveshaft 22, to affix the position of the beater 12.
The second adjustment that is available to the owners of prior art pedals is the adjustment of the pre-load length of spring 34. This is accomplished by the rotation of nut 42 on threaded rod 38. This movement either extends or retracts rod 38 from the upper end of flange 40, thereby effectively increasing or decreasing the spring length.
While both of these adjustments are useful to the drum player, they do not provide the type of additional adjustment that accomplished players desire. For example, a player typically desires to have the beginning of the down-stroke of the pedal with little bias from the return spring, to enable the beater to rapidly increase speed. Then, as the beater approaches the drumhead, the player desires the bias to be geometrically greater, to enable a faster withdrawal of the beater hammer from the drumhead—and thereby permit a faster repeat of the stroke. Thus, it is desired to vary the increase in tension of the spring between the rest position and the impact position. This is not possible with prior art pedals.
As shown in FIG. 2, if it is assumed that the footplate is depressed at a constant speed throughout a stroke, the prior art pedal will have a ratio of driveshaft rotation to spring tension that has a constant, straight slope S1 to the point of impact. The beater is then returned with a negative backlash by virtue of the bias of spring 34 applied to the beater. Because there is no rearward or “negative” force applied to the beater other than the spring force, the momentum of the beater will cause the beater to travel past the rest position, but only a short distance—typically about one-half the amount of forward rotation during the impact stroke. If the player does not depress the footplate again for another stroke of the pedal, the spring 34 will eventually return the pedal to the rest position.
Because a spring provides a constant biasing force throughout the distance that it is stretched, the adjustment of the overall length of the spring does not change the slope of the line—which represents the ratio of driveshaft rotation to spring bias. Rather, the change will increase both the preload force and the total force required at the impact position, by the same amount. Thus, while the amount of force required at the impact position is greater, as desired, the amount of resistance encountered at the beginning of the stroke is also increased—which is contrary to what is desired.
Similarly, changing the rest position of the beater will not change the slope of the line. Rather, it simply increases or decreases the distance through which the beater must travel to impact the drumhead.